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  • 1
    Electronic Resource
    Electronic Resource
    Pollinator foraging behavior and pollen collection on the floral morphs of tristylous Pontederia cordata L. (1987)
    Springer
    Oecologia 74 (1987), S. 347-351 
    Details
    ISSN: 1432-1939
    Keywords: Pontederia cordata ; Bombus ; Tristyly ; Pollination ; Behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The foraging behavior of the pollinators of tristylous Pontederia cordata was studied to determine if differences in floral morphology would lead to preferential visitation of the floral morphs. Although nectar production is not different in the three floral morphs, differences in the production and size of pollen grains produced by the three anther levels results in the morphs offering variable amounts of resources to pollen-collecting insects. Bumblebees (Bombus spp.) and the solitary bee Melissodes apicata used P. cordata primarily as a nectar source and therefore did not seem to exhibit any morph preference. In contrast, honeybees visited flowers mainly for pollen and preferred to forage on long-level anthers of the short-and mid-styled morphs. An analysis of the composition of corbicular pollen loads indicated that, relative to the frequency of production in the population: 1) honeybees collected an excess of pollen from long-level anthers; 2) bumblebees collected the three types of pollen without any apparent preference; and 3) M. apicata preferentially collected pollen from the short-level anthers — presumably because their proboscides are modified by the presence of tiny hairs. The results suggest that P. cordata in Ontario is serviced by a diverse, unspecialized pollinator fauna which is not co-adapted to the tristylous floral polymorphism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378928
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Unknown
    LANDSAT survey of near-shore ice conditions along the Arctic coast of Alaska (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The author has identified the following significant results. Winter and spring near-shore ice conditions were analyzed for the Beaufort Sea 1973-77, and the Chukchi Sea 1973-76. LANDSAT imagery was utilized to map major ice features related to regional ice morphology. Significant features from individual LANDSAT image maps were combined to yield regional maps of major ice ridge systems for each year of study and maps of flaw lead systems for representative seasons during each year. These regional maps were, in turn, used to prepare seasonal ice morphology maps. These maps showed, in terms of a zonal analysis, regions of statistically uniform ice behavior. The behavioral characteristics of each zone were described in terms of coastal processes and bathymetric configuration.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: E78-10136 , NASA-CR-157148
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Growth mechanisms of 'Katie's Floeberg' (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The growth mechanism of the grounded ice feature on Hanna's Shoal, located at approximately 162 deg W, 72 deg N in the Chukchi Sea, has been analyzed using Landsat I and II satellite imagery. The primary mechanism of growth was deduced to be the formation of large wedges of ice against the upstream edge of the feature. These wedges of piled ice form in three stages and may or may not become permanently affixed to the core of the feature. Remains of these growth patterns can sometimes be seen in the interior of the feature on the satellite imagery.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Arctic and Alpine Research; 10; 4, 19; 1978
    Format: text
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    NASA TECHNICAL REPORTS
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